Common control for electrical tuners and couplers



Feb. 21, 1950 Filed March 30, 1945 A. E- HARRISON COMMON CONTROL FOR ELECTRICAL TUNERS AND COUPLERS 2 Sheets-Sheet 1 /2 FIG.

POWER OSCILLA TOR AMPLIFIER (PL mm 9 3 CONTROL CONTROL UNIT UNIT l 54 2/ fill-4075 (aw-01. UNIT FIG. 2

45- 43 46 2 -33 3a 44 I 34 E l I l 9 l I: 39 2 37 16 E l I E r v E 71 E q l E l l 1 E as E INVENTOQ A. EWARRISON A TTORNEV Feb. 21, 1950 A. E. HARRISON 2,498,078

COMMON CONTROL FOR ELECTRICAL TUNERS AND COUPLERS Filed March 30, 1945 2 Sheets-Sheet 2 FIG. 3

POSITION 0F SHAFT as mum/r09 .4. HARRISON A T TOFPNEV Patented Feb. 21, 1950 COMMON CONTROL FOR ELECTRICAL TUNERS AND COUPLERS Arthur E. Harrison, Short Hills, N. J assignor to Bell Telephone Laboratories, Incorporated, New York, N. Y., a corporation of New York Application March 30, 1945, Serial No. 585,627

3 Claims.

This invention relates to control systems and particularly to tuning controls for radio apparatus and has for an object to improve such controls.

-In the use of radio transmitters and receivers it is often desirable to provide controls for readily shifting the frequency between several preset values either directly at the apparatus or from a remote point. In the case of receivers this can usually be done by ganging all of the tuning devices and operating them by a single control element. However, in the case of transmitters it is generally difiicult if not impossible to gang all the tuning units, accordingly several controls are required. In the case of radio equipment for vehicles and particularly for aircraft, space and weight limitations are quite critical and it is necessary to keep the number of individual control units to a minimum.

()ne control that is necessary to the eificient operation of a radio transmitter is the matching of the impedance of the output circuit to that of the transmission line leading to the antenna. This adjustment requires a control of both the resistive and reactive components of the impedance. In the case of equipment for general use such as a transmitter for use in various types of airplanes with the resultant wide variations in antennas and lengths of transmission line, the impedance conditions encountered are so varied that there cannot be maintained such a fixed relation of resistance to reactance as would permit a single ganged control. This problem is accentuated in equipment operating over wide frequency bands. On the other hand space and weight requirements may be such as to prevent the use of separate control units.

In accordance with a feature of this invention the controls for the resistance and reactance components of an impedance matching system are so geared together that one control goes through its range of Variation several times while the other goes through its range only .once. As a result the combined control can be driven by a single unit and any of several values of the first component can be obtained for each value of the second.

The invention may be better understood by reference to the following detailed description in connection with the drawing in which:

Fig. 1 is a schematic circuit diagram of one embodiment of the invention in a radio transmitter;

Fig. 2' is a mechanical drawing of the impedance matching system of Fig. l; and

Fig. 3 is an explanatory diagram.

Fig. 1 shows in block schematic a radio transmitter comprising an oscillator [0, a first amplifier H and a power amplifier 12. The output of the power amplifier is fed over a coaxial line l3 to an antenna l4. A matching circuit l5 is provided to obtain impedance matching between the line l3 and the amplifier I2. The matching circuit I5 comprises a coupling inductor l6 having a variable output tap and shunted by a variable condenser H. The input to the matching circuit I5 is supplied through a primary coil l8 coupled to the inductor l6 and forming part of a link circuit coupled to the plate inductors I9 of the power amplifier 2.

In order to permit rapid tuning of the transmitter to any of several preset frequencies either locally or from a remote position two control units 20 and 2| are provided. Each operates to position its shaft to any of several predetermined positions and to set the tuning elements connected to the shafts accordingly. They are interconnected to be operated together; for example, by electrical connections to a remote control unit 28. These control units 20 and 2 I, including their interconnection to the remote control unit 28, may be of the type disclosed in Patent 2285,41 3: to A. A. Collins of June 9, 1942, for example.

Unit 20 controls the tuning of the oscillator l0 and amplifiers l and I2 which have their tuning units ganged on the shaft 22. The unit 2| controls the adjustment of the matching circuit l5 through the shaft 23. This will be described in detail with particular reference to Fig. 2.

The construction of the matching circuit l5 particularly adapted for use at ultra-high frequencies is shown in Fig. 2. This comprises a main frame including a base 3| and two end plates 32 and 33. A shaft 34 is journaled in the end plates 32 and 33. Carried on or integral with the shaft 34 is a coil form 35. Wound in a threaded groove in the form 35 is the coupling coil IS, the grounded end of which is brought out through a slip ring 36 and resilient wiper 31 to the terminal 38. The other end of the coil |B is brought out through the slip ring 39 and resilient brush 40 to the terminal 4|.

The coupling coil l8 of the link'circuit is of the self-supporting type and is mounted with its ends secured in the insulating block 42 mounted on the base member 3|. An adjustable tap is brought out from the coil l6 by means of rollertype wiper 43. A shaft 44 supported by the resilient arms 45 and 46 carries the roller 43. The resilient arms 45 and 46 are supported by the member 41 attached to the end plate 32 and serve to keep the roller 43 in good contact with the plates 50.- and. a set: oi. rotor plates; 51 both of,

semi-circular shape. The condenser is connected in shunt to the coil [6, the stator plates 50 being connected to the high voltage end of the coil at the terminal 4| and the rotor b'eingconnectedto,

the grounded end at the terminal 38 through the resilient wiper 52.

The shaft 23 driven by the control unit-2d: drivesv the shaft 34 and consequently the coil lfi throughthe bevel gears 53. This causes-the roller con.- tact 43 to move along the coil It thus varying the taping point thereon. At the same tirne the rotor is driven through the gears 54 and 55, which have such;- aratiothat the;- rotor 5 1; makes two'and onerhalf revolutions for each revolution ofthe; coil, [6; Thesystemi is designed so that the rotor contact 43*followstheicoilfor two-turns f01"t1'lecomplete range; of angular adjustment provided by the: control. unit 2.3. Accordingly there area total-of tenresonance points provided by the; condenser. 11 within the same. range of the control unit 2 lbecauseof! the fact that there are two resonance points (i-. e;,. capacity values) for eachv revolution; of ,therotor 5l;one upon the. rotor; plates: entering theastator plates and the other'upon; theirrlea'vingr As; av result, for any resonance value, or more properlyfor any react,- ance value as determinedbyrthecondenser I! at any; particular-position. in; parallel with the coil I6 there will be. anyof; ten different values of resistance: as determined; by: the: possible positions of therotor-contact. on the-coil t6:

Theo-perationz oii. the impedance matchin circuit inthis manner; can: be betterunderstood by reference to;-thetdiagramsaofili ig. 3; wherein positions of? the sha-ftlii: (as-determined by the control unit 211-) aregplottedasr abcissae. and: values of resistance as determined by'the positions of the rotor contact. 4 3v on; coil; I18 are; shown by the dotted curve; 5.8: and along; the. left-hand vertical scale; while: corresponding values of reactance as determinedi by the positions. of the; rotor 5| are shownby the-:full line curve and along the righthandzverticar. scale. Thus; it may be seen that any value. ofreactanca,forexample; +K. onthe righthand scale; can be-obtained: atxanyof ten positions: of the shaft; 23:, On: the other; hand, for each of ithese; shaft positions; therewill be a different value of resistance. as. indicated by the dotted. curve, 58 and: shown; by: the values A to'J or a the left-handtscalez, Accordingly; the device provides asconsiderable.fiexibility'in the choice of relative values of reactanccrand, resistance permittinggimpedance matching with a: considerable variety of antennae: andt'lengthss of the connecting. line. 133;: The: degree of' flexibility in anycase is determined by thearati'o; of the drive of the ccupling'coil.anctcond'enseri and the particular values hereina usedi area. for: purposesv ofi illustra tion-only; Thelpreoi sion offfadjustment is directly proportionaltmthedrive ratio which may Ice-made any practical value as required for any particular application.

In setting up the control unit 2| for any particular frequency it will be observed that as the unit 21 is moved through its range to turn the shaft 23-1therewill be a series; of. ten peak indications; on the, field strength; antenna current or other meter used as an indicator. That position at which the highest of these peaks occurs is chosen asthe. position for that frequency.

What isgclaimed'isz 1; In combination, a variable capacitor, an inductorghavingv avariable tap and being connected in parallelwith said variable capacitor, an output circuit connected to said variable tap, and a drive. for, simultaneously operating said variable capacitor and said'variable tap at different speeds to 'vary said capacitor through its range of variations a plurality of times for each single varia tion of said taplthrough itsrangel 2; In aradio-transmitter, an. oscillator and amplifiersystem-means for tuning said system, to any of a plurality of preset frequencies, a load circuit, an output" circuit. for, couplin said amplifier-to said-load circuit comprising a variable reactor and; a coupling unit having a coefiicient of coupling'variableover a range; and. means for adjusting said output'circuit for operation at any of said plurality of preset. frequencies comprising means for driving said variable: reactor: through itsirangeg of variations-- a plurality of times while simultaneously driving, saidi variable coupling through the; range; of variations of its coefficient of coupling a singleztime;

3: In an electrical system. for coupling an input: circuit to; load. circuits ofa. range ofv impedances for theefiicient supply thereto. Off oscillatory electrical energy of a range of. frequencies, coupling means having a coupling. coefficient variable over a predeterminedrrangera reactor: of. re.- actance value variable, over a predetermined range, and adrive: for simultaneously varying the reactance value. of: said reactor'and, the coeiiicient of coupling of said coupling means at such relative rates that:the=reactance; value of said reactor varies over its said, range: a plurality of; times for each variation of the. coupling coeificient over its said range;

' HARRISON.

REEERENGES. CITED.

The following references are of record in the file of this patent:

UNITED STATES PATENTS,

I 642,948 France Sept; 6, 1928 

